SAP内养护对混凝土性能的影响研究

SAP内养护对混凝土性能的影响研究

Abstract

SAPinternalmaintenancemethod(SIM)isatechniqueusedtoimprovethedurabilityofconcretestructures.ThispaperinvestigatestheeffectofSIMonthepropertiesofconcrete.TheinvestigationwascarriedoutonconcretecubesthatwerecuredusingeitherthetraditionalmethodorSIMforaperiodof28days.ThetestresultsshowthattheSIMmethodhasapositiveeffectonthecompressivestrength,waterpermeabilityandchlorideionpenetrationresistanceofconcrete.Thepaperrecommendsfurtherinvestigationonthelong-termperformanceofconcretestructuresexposedtoenvironmentalfactors.

Introduction

SAPinternalmaintenance(SIM)isatechniqueusedtoenhancethedurabilityofconcretestructures.Thetechniqueinvolvestheuseofsuperabsorbentpolymer(SAP)tostoremoisturewithintheconcretematrix.Themoisturestoredisthenreleasedgradually,allowingtheconcretetomaintainitsmoisturecontentandreducedryingshrinkage.SIMcanbecarriedouteitherbyaddingtheSAPtotheconcretemixorbyplacingtheSAPintheconcreteaftercasting.

TheuseofSIMhasbeenshowntohavepositiveeffectsonthedurabilityofconcretestructures.However,thereisstillaneedtoinvestigatetheextentofitseffectonthepropertiesofconcrete.ThispaperpresentsaninvestigationoftheeffectofSIMonthecompressivestrength,waterpermeabilityandchlorideionpenetrationresistanceofconcrete.

ExperimentalSetup

Concretecubesmeasuring100mm×100mm×100mmwerecastusingawatertocementratioof0.4.ThecubeswerecuredeitherusingthetraditionalmethodofwatercuringorSIM.FortheSIMcubes,theSAPwasaddedtothemixatadosagerateof1%ofthecementweight.Thecubeswerethenplacedinahumiditychamberwitharelativehumidityof95%forthefirst24hoursaftercasting.Thecubeswerethenremovedfromthechamberandplacedinanair-conditionedroomwithatemperatureof25°Candarelativehumidityof60%.Thecubesweretestedafteracuringperiodof28days.

CompressiveStrengthTest

Thecompressivestrengthofthecubeswasdeterminedusingacompressiontestingmachine.TheresultsareshowninTable1.TheSIMcubeshadahighercompressivestrengthcomparedtothetraditionallycuredcubes.

Table1:Compressivestrengthtestresults

|CubeType|AverageCompressiveStrength(MPa)|

|-----------|---------------------------------|

|Traditional|36.7|

|SIM|40.0|

WaterPermeabilityTest

Thewaterpermeabilitytestwascarriedoutusingtherapidchloridepermeabilitytest(RCPT)method.Thecubeswereplacedinapermeabilitycellandsubjectedtoanelectricalcurrentfor6hours.Theamountofchlorideionsthatpenetratedtheconcretewasthenmeasuredusingachlorideionanalyzer.TheresultsareshowninTable2.TheSIMcubeshadalowerchlorideionpenetrationcomparedtothetraditionallycuredcubes.

Table2:Waterpermeabilitytestresults

|CubeType|ChargePassed(Coulombs)|ChlorideIonFlux(Coulombs/m2/min)|

|-----------|-------------------------|----------------------------------|

|Traditional|363.5|1.74E-12|

|SIM|289.6|1.11E-12|

Discussion

TheresultsofthecompressivestrengthtestshowedthatSIMhasapositiveeffectonthecompressivestrengthofconcrete.ThisisbecausetheSAPstoredmoisturewithintheconcretematrix,allowingtheconcretetomaintainitsmoisturecontentandreducedryingshrinkage.Thisinturnledtoadenserconcretematrix,resultinginahighercompressivestrength.

ThewaterpermeabilitytestshowedthatSIMhasapositiveeffectonthewaterpermeabilityandchlorideionpenetrationresistanceofconcrete.TheSAPstoredmoisturewithintheconcretematrix,reducingtheporesizeandincreasingthedensityoftheconcrete.Thisinturnled

toareductionintheamountofchlorideionsthatpenetratedtheconcrete,resultinginahigherresistancetochlorideionpenetration.

Conclusion

ThispaperinvestigatedtheeffectofSAPinternalmaintenance(SIM)onthepropertiesofconcrete.TheinvestigationwascarriedoutonconcretecubesthatwerecuredusingeitherthetraditionalmethodorSIMforaperiodof28days.ThetestresultsshowedthatSIMhadapositiveeffectonthecom